ORAU TEAM

Dose Reconstruction

Project for NIOSH

Oak Ridge Associated Universities I Dade Moeller & Associates I MJW Corporation

Page 1 of 8

Document Title:

Paducah Gaseous Diffusion Plant – Introduction

Document Number: ORAUT-TKBS-0019-1 

Revision: 01

Effective Date: 04/02/2007

Type of Document TBD

Supersedes: Revision 00

Subject Expert(s): Daniel S. Mantooth

Site Expert(s): N/A

Approval: Signature on File Approval Date: 04/02/2007

Daniel S. Mantooth, Document Owner

Concurrence: Signature on File Concurrence Date: 03/23/2007

John M. Byrne, Task 3 Manager

Concurrence: Signature on File Concurrence Date: 03/22/2007

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Concurrence Date: 03/27/2007

Kate Kimpan, Project Director

Approval: Signature on File Approval Date: 04/02/2007

James W. Neton, Associate Director for Science

 New Total Rewrite Revision Page Change

FOR DOCUMENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE, REPLACE THE PRIOR 

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-TKBS-0019-1 Revision No. 01 Effective Date: 04/02/2007 Page 2 of 8

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

09/09/2004 00 First approved issue. Initiated by Jay J. Maisler.

08/30/2006 00 PC-1 Approved page change revision to review against Worker Outreach 

comments and periodic revision. Updates required language on 

page 4 in Section 1.0. No sections were deleted. No further 

changes occurred as a result of internal formal review. This revision 

results in no change to the assigned dose and no PER is required. 

Training required: As determined by the Task Manager. Initiated by 

Paul A. Szalinski. Approval: 

Daniel Mantooth, TBD Team Leader

Signature on File 08/16/2006

John M. Byrne, Task 3 Manager

Richard Merrill Signature on File for 08/16/2006

Edward F. Maher, Task 5 Manager

Signature on File 08/16/2006

Kate Kimpan, Project Director

Signature on File 08/17/2006

James W. Neton, Associate Director for Science

Signature on File 08/30/2006

04/02/2007 01 Approved Rev 01 revised to incorporate Attributions and Annotations 

Section 1.3 and update the References section. Constitutes a total 

rewrite of the document. No further changes occurred as a result of 

internal formal review. Incorporates NIOSH formal review 

comments. This revision results in no change to the assigned dose

and no PER is required. Training required: As determined by the 

Task Manager. Initiated by Daniel S. Mantooth.
Document No. ORAUT-TKBS-0019-1 Revision No. 01 Effective Date: 04/02/2007 Page 3 of 8

TABLE OF CONTENTS

SECTION TITLE

Acronyms and Abbreviations ...............................................................................................................

PAGE

4

1.1 Purpose ......................................................................................................................................5

1.2 Scope .........................................................................................................................................6

1.3 Attributions and Annotations .......................................................................................................7

References ..........................................................................................................................................8
Document No. ORAUT-TKBS-0019-1 Revision No. 01 Effective Date: 04/02/2007 Page 4 of 8

ACRONYMS AND ABBREVIATIONS

DOE U.S. Department of Energy

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

kerma kinetic energy released per unit mass

NIOSH National Institute for Occupational Safety and Health

PGDP Paducah Gaseous Diffusion Plant

POC probability of causation

TBD technical basis document

U.S.C. United States Code

§ section or sections
Document No. ORAUT-TKBS-0019-1 Revision No. 01 Effective Date: 04/02/2007 Page 5 of 8

1.1 PURPOSE

Technical basis documents and site profile documents are not official determinations made by the 

National Institute for Occupational Safety and Health (NIOSH) but are rather general working 

documents that provide historical background information and guidance to assist in the preparation of 

dose reconstructions for particular sites or categories of sites. They will be revised in the event 

additional relevant information is obtained about the affected site(s). These documents may be used 

to assist NIOSH staff in the completion of the individual work required for each dose reconstruction.

In this document the word “facility” is used as a general term for an area, building, or group of 

buildings that served a specific purpose at a site. It does not necessarily connote an “atomic weapons 

employer facility” or a “Department of Energy [DOE] facility” as defined in the Energy Employees 

Occupational Illness Compensation Program Act [EEOICPA; 42 U.S.C. § 7384l(5) and (12)]. 

EEOICPA defines a DOE facility as “any building, structure, or premise, including the grounds upon 

which such building, structure, or premise is located ... in which operations are, or have been, 

conducted by, or on behalf of, the Department of Energy (except for buildings, structures, premises, 

grounds, or operations ... pertaining to the Naval Nuclear Propulsion Program)” [42 U.S.C. § 

7384l(12)]. Accordingly, except for the exclusion for the Naval Nuclear Propulsion Program noted 

above, any facility that performs or performed DOE operations of any nature whatsoever is a DOE 

facility encompassed by EEOICPA.

For employees of DOE or its contractors with cancer, the DOE facility definition only determines 

eligibility for a dose reconstruction, which is a prerequisite to a compensation decision (except for 

members of the Special Exposure Cohort). The compensation decision for cancer claimants is based 

on a section of the statute entitled “Exposure in the Performance of Duty.” That provision [42 U.S.C. § 

7384n(b)] says that an individual with cancer “shall be determined to have sustained that cancer in the 

performance of duty for purposes of the compensation program if, and only if, the cancer ... was at 

least as likely as not related to employment at the facility [where the employee worked], as 

determined in accordance with the POC [probability of causation1

As noted above, the statute includes a definition of a DOE facility that excludes “buildings, structures, 

premises, grounds, or operations covered by Executive Order No. 12344, dated February 1, 1982 (42 

U.S.C. 7158 note), pertaining to the Naval Nuclear Propulsion Program” [42 U.S.C. § 7384l(12)]. 

While this definition contains an exclusion with respect to the Naval Nuclear Propulsion Program, the 

section of EEOICPA that deals with the compensation decision for covered employees with cancer 

[i.e., 42 U.S.C. § 7384n(b), entitled “Exposure in the Performance of Duty”] does not contain such an 

exclusion. Therefore, the statute requires NIOSH to include all occupationally derived radiation 

exposures at covered facilities in its dose reconstructions for employees at DOE facilities, including 

radiation exposures related to the Naval Nuclear Propulsion Program. As a result, all internal and 

external dosimetry monitoring results are considered valid for use in dose reconstruction. No efforts 

are made to determine the eligibility of any fraction of total measured exposure for inclusion in dose 

reconstruction. NIOSH, however, does not consider the following exposures to be occupationally 

derived:

] guidelines established under 

subsection (c) ...” [42 U.S.C. § 7384n(b)]. Neither the statute nor the probability of causation 

guidelines (nor the dose reconstruction regulation) define “performance of duty” for DOE employees 

with a covered cancer or restrict the “duty” to nuclear weapons work.

• Radiation from naturally occurring radon present in conventional structures

• Radiation from diagnostic X-rays received in the treatment of work-related injuries

 

1 The U.S. Department of Labor is ultimately responsible under the EEOICPA for determining the POC. 
Document No. ORAUT-TKBS-0019-1 Revision No. 01 Effective Date: 04/02/2007 Page 6 of 8

1.2 SCOPE 

The Paducah Gaseous Diffusion Plant (PGDP) Site Profile is divided into six major sections – this 

Introduction, Site Description, Occupational Medical Dose, Occupational Environmental Dose, 

Occupational Internal Dose, and Occupational External Dose. Some sections are accompanied by an 

attachment that provides the critical data for the specialists reconstructing the doses.

The Site Description TBD (ORAUT 2006a) is a brief description of the facilities and processes that 

PGDP used to process and enrich uranium. The purpose of the gaseous diffusion plant has been and 

continues to be the enrichment of uranium, initially for military applications and subsequently for 

commercial nuclear reactor fuel. PGDP enriches feed material in the form of uranium hexafluoride 

gas (UF6) from approximately 0.711% 235U up to about 2.5% 235U. The enriched product from PGDP 

has been sent to other U. S. Department of Energy (DOE) gaseous diffusion plants at Portsmouth, 

Ohio, and Oak Ridge, Tennessee, for further enrichment. Some feed material was recycled uranium 

from spent reactor fuel.

The Occupational Medical Dose TBD (ORAUT 2006b) provides information about the doses individual 

workers received from X-rays that were required as a condition of employment. The PGDP 

occupational medicine program required preemployment and regular diagnostic chest X-ray 

examinations. The examinations consisted of one posterior-anterior and one lateral chest projection. 

In addition to parts of the body exposed in the primary beam of an X-ray machine, other tissues 

received some dose from secondary radiation. Secondary radiation consists of X-rays that are 

scattered from surrounding materials or that escape from the source assembly. This TBD provides 

tables that list estimated dose equivalents to organs of the body that result from single and combined 

posterior-anterior and lateral chest X-rays for male and female PGDP employees; these estimates are 

favorable to claimants. The tables are derived from an assessment of the air kerma at the source-toskin distance based on specific operating parameters for the facility, insofar as these are known.

The Occupational Environmental Dose TBD (ORAUT 2006c) applies to workers who were not 

monitored for external or internal radiation exposure. The environmental dose is the dose workers 

received when working on the site but outside the buildings from inhalation of radioactive materials in 

the air and direct radiation exposure from sources such as the depleted uranium hexafluoride 

cylinders in storage.

Inhalation of environmental radionuclides results in internal dose to the whole body or body organs. 

The internal dose for workers outside of the facilities was determined from the air concentrations that 

were a result of the releases from stacks, individual building releases, and from the purge cascade 

and other operations at PGDP. Unmonitored workers might have been incurred occupational doses 

internally from onsite releases to the air. Air concentrations of radionuclides were determined using 

annual environmental reports for the period from 1952 through 1996. Values for airborne 

concentrations and annual intakes are provided for total uranium and 99Tc.

Site annual environmental reports, health physics surveys, and other reports were reviewed for data 

that would be useful in reconstructing ambient radiation levels. Ambient radiation dose rates include 

natural background radiation and sources within the site. 

PGDP personnel have annually compared these data with thermoluminescent dosimeter data from 

offsite locations and literature values for State of Kentucky and regional exposure levels. The 

determination has always been that onsite ambient radiological conditions as measured at the 

security fence are not significantly different from offsite, State, and regional annual exposure levels. 

This is attributed to the geology of the region around PGDP. Exceptions to this observation have 
Document No. ORAUT-TKBS-0019-1 Revision No. 01 Effective Date: 04/02/2007 Page 7 of 8

been monitoring locations near depleted uranium cylinder storage yards in recent years. These 

locations have shown increases in external exposure as the inventory of depleted uranium has 

increased. The approach for estimating external dose using this information is provided in the TBD.

The Occupational Internal Dosimetry TBD (ORAUT 2007) describes the internal dosimetry program at 

PGDP. The primary method for monitoring employees for intakes of radionuclides at PGDP was urine 

bioassay, which was instituted at the start of enrichment operations and has continued to the present 

day. However, the focus of the monitoring program in the early years was the detection of excreted 

soluble uranium. When monitoring for less soluble isotopes of uranium and transuranic elements was 

necessary, in vivo methodologies were implemented to supplement the excretion data. These 

methods were primarily whole-body counting and chest (lung) counting.

Until the mid-1980s, action levels were set based on the amount of uranium excreted. Later, intakes 

and doses were assessed based upon both in vivo and in vitro monitoring results. Data are available 

from 1952 to the present for both in vivo and in vitro analysis records and associated interpretations.

A review of in-house procedures used to assess the concentration of uranium in urine indicates that a 

variety of quality control steps were an integral part of the process. Therefore, the in vitro results from 

in-house processing, typically reported in units of micrograms of uranium per liter, are considered to 

be generally reliable. However, interpretation of those results can be difficult primarily because of 

uncertainties about enrichment and solubility, the contribution of environmental uranium, and because 

samples were collected at work and during the middle of the work week, meaning that crosscontamination and the inability to separate soluble and insoluble intake fractions.

Guidance on selection of source terms is provided in the TBD. Input parameters for the interpretation 

of in vivo and in vitro measurement results are presented and include instructions for assessing dose 

for both monitored and unmonitored employees. The detection limits of the various in vivo and in vitro 

methodologies and potential missed dose are discussed. Existing data analysis is summarized, and 

significant incidents with internal dose potential are identified.

The Occupational External Dosimetry TBD (ORAUT 2006d) describes the program for measuring skin 

and whole-body doses to the workers from sources that were external to the body. The methods 

used at the PGDP have also evolved over the years as new techniques and equipment have been 

developed. In addition, concepts in radiation protection have changed. Dose reconstruction, PGDP 

practices and policies, and dosimeter types and technology for measuring the dose from the different 

types of radiation are discussed in this section. Attention is given to the evaluation of doses 

measured from exposure to beta, gamma, and neutron radiation.

Sources of bias, workplace radiation field characteristics, responses of different beta/gamma and 

neutron dosimeters in the workplace fields, and the adjustments to the recorded dose measured by 

these dosimeters during specific years are presented in detail. In addition, the sources of potential 

dose that could be missed because of the limitations of dosimetry systems and the methods of 

reporting low doses are presented as a function of dosimeter type, year, and type of radiation.

1.3 ATTRIBUTIONS AND ANNOTATIONS

All information requiring identification was addressed via references integrated into the reference 

section of this document.
Document No. ORAUT-TKBS-0019-1 Revision No. 01 Effective Date: 04/02/2007 Page 8 of 8

REFERENCES

ORAUT (Oak Ridge Associated Universities Team), 2006a, Paducah Gaseous Diffusion Plant – Site 

Description, ORAUT-TKBS-0019-2, Rev. 01, Oak Ridge, Tennessee, August 21.

ORAUT (Oak Ridge Associated Universities Team), 2006b, Paducah Gaseous Diffusion Plant – 

Occupational Medical Dose, ORAUT-TKBS-0019-3, Rev. 01, Oak Ridge, Tennessee,

September 26.

ORAUT (Oak Ridge Associated Universities Team), 2006c, Paducah Gaseous Diffusion Plant – 

Occupational Environmental Dose, ORAUT-TKBS-0019-4, Rev. 01, Oak Ridge, Tennessee,

November 7.

ORAUT (Oak Ridge Associated Universities Team), 2006d, Paducah Gaseous Diffusion Plant – 

Occupational External Dose, ORAUT-TKBS-0019-6, Rev. 02, Oak Ridge, Tennessee, August 

30.

ORAUT (Oak Ridge Associated Universities Team), 2007, Paducah Gaseous Diffusion Plant – 

Occupational Internal Dose, ORAUT-TKBS-0019-5, Rev. 01 PC-1, Oak Ridge, Tennessee,

January 31.